The invention relates to a paving composition for use in road construction and related applications. In particular, the invention relates to an asphalt-based paving composition with an anti-stripping agent to improve the adhesion of the asphalt to mineral aggregate.
Bituminous materials, such as asphalt, have been used in the building of roadways, driveways, and the like. In addition to asphalt, mineral aggregates are also used to increase the strength and to prolong the life of such surfaces. In road construction, bitumen-aggregate mixtures are applied to the road surface. These bitumen-aggregate mixtures generally can be obtained by mixing anionic or cationic asphalt emulsions with a mineral aggregate, such as stone chips, gravel or sand, or by mixing free flowing heated asphalt (asphalt cement) with a pre-dried mineral aggregate, by a hot mix process. The pre-dried aggregate can also be mixed with asphalt diluted in a hydrocarbon solvent, known as cutback asphalt.
The quality of the road surface is generally dependent upon the strength of the bonds between the asphalt and aggregate after setting of the composition. Poor service performance is, in part, due to poor adhesion between the asphalt and aggregate, resulting in the stripping off of the asphalt from the aggregate surface.
Asphalt compositions have relatively poor adhesion to mineral aggregates in the presence of water. Since the aggregate is preferentially wetted by water, even if the aggregate is dry at the time it is blended with the asphalt, the eventual penetration of water into the composition reaches the aggregate and interferes with the bond between the aggregate and the asphalt. The result of this stripping is flaked pavement and pot holes. Stripping problems also generally occur if the aggregate is poorly dried, if sandy carbonate aggregate containing a large amount of quartz particles is used, if carbonate aggregate is covered with dust, or if igneous (silicate) aggregates, such as granite, diorite, gabbro, diabase, or basalt, that strip in the presence of external water are used. To avoid such failures, adhesion improving agents known as xe2x80x9canti-stripping agentsxe2x80x9d are commonly added to the asphalt. Before the mixing operation, these agents are added to the bituminous binder to reduce its surface tension and to induce on the binder an electrical charge opposite to that of the aggregate surface. Lower surface tension gives improved wettability of the aggregate, and charge reversal enhances bond strength by increasing Coulomb""s attractive forces.
Cationic substances, particularly amines, have been traditionally used as anti-stripping agents. The cationic substances increase the hydrophobicity of the aggregate, making the aggregate resistant to the penetration of water so that water seeping into the asphalt does not tend to destroy the bond between the asphalt and the aggregate. The addition of the cationic substances tends to make the aggregate sufficiently water resistant that a good bond with the asphalt is formed. Among the cationic materials which have been used as adhesion promoters with asphalt are primary alkyl amines (such as lauryl amine and stearyl amine) and alkylene diamines (such as the fatty alkyl substituted alkylene diamines). Because these amines may rapidly lose their activity when combined with asphalt and stored at elevated temperatures for an extended period, it has therefore been necessary to combine the amine with the asphalt at the work site when the asphalt is combined with the aggregate, which in practice presents difficulties in obtaining a homogeneous mixture. It is also noted that these amines are generally corrosive and may have an unpleasant smell.
Various asphalt formulations have been reported in attempts to enhance the properties of paving compositions while avoiding the above-described difficulties. U.S. Pat. No. 4,447,269 offers cationic oil in water type bituminous aggregate slurries. The emulsion comprises bitumen and a reaction product of a polyamine and a polycarboxylic acid, and water. Lime or cement can be added to reduce the setting time of the mixture.
U.S. Pat. No. 4,721,529 suggests the preparation and use of asphalt admixtures with the reaction product of an amine antistrip and an acid salt. The acid salt is a divalent or trivalent metal salt of an inorganic acid.
U.S. Pat. No. 5,443,632 suggests cationic aqueous bituminous emulsion-aggregate paving slurry seal mixtures. The emulsifier is the product of reaction of polyamines with fatty acids and rosing, and a quaternizing agent.
U.S. Pat. No. 4,806,166 proposes preparation of an aggregate comprising asphalt and an adhesion improving amount of an anti-stripping agent comprising the aminoester reaction product of a tall oil fatty acid and triethanolamine. The reaction product is of low viscosity, has good coating performance, and is inexpensive.
U.S. Pat. No. 5,019,610 offers an asphalt composition comprising a blend of a thermoplastic rubber polymer and a fatty dialkyl amide, and asphalt cement. The preparation method requires only gentle stirring. The amide has a C6-C22 alkyl group attached to the carbonyl, and two C1-C8 alkyl groups attached to the amide nitrogen. The compositions offer good viscosities at relatively low residue percentages. The compositions are offered for use in road paving, asphalt roofing cements, mastics, moisture barriers, joint and crack fillers, and sheeting.
U.S. Pat. No. 4,430,127 suggests preparation of a bitumen and epoxylated polyamine composition. The compositions provide improved adhesion between aggregate materials and the bitumen material. At least two of the amino nitrogen atoms are separated by six carbon atoms.
U.S. Pat. No. 4,462,840 proposes use of a cation-active emulsifier which is the product of a polyamine and polycarboxylic acids. The emulsifier is useful in producing aqueous bituminous emulsion-aggregate slurries.
Although significant effort has been spent on improving the adhesion between mineral aggregates and asphalt, there continues to exist a need for paving compositions with improved adhesion between mineral aggregate and asphalt. Preferably, the paving compositions should not have an unpleasant odor or smell.
Paving compositions comprising a bituminous material such as asphalt and an amide compound are disclosed. The amide is preferably a diamide. The compositions can further comprise mineral aggregates or other materials suitable for use in paving applications. The compositions can be used in new road construction, or in road repair applications.
Embodiments of the invention provide a paving composition and methods for making and using the composition. The paving composition comprises a bituminous material, such as asphalt, and a reaction product of at least one polycarboxylic acid reacted with at least one polyamine or amine. Preferably, the composition is substantially free of water. The composition is preferably not an emulsion. The paving composition can further include mineral aggregate mixed with the bituminous material and the reaction product. Preferably, the reaction product of the polycarboxylic acid and the polyamine or amine is an amide compound. The amide compound includes one or more amide functional groups: 
Preferably, the amide compound is a diamide or a compound including multiple amide functional groups (i.e., three or more amide functional groups). The term xe2x80x9cmultiamide compoundxe2x80x9d used herein refers to an amide compound with two, three, four, five, six, seven, or more amide groups per molecule. In some embodiments, polymeric amide or polyamide is used as an anti-stripping agent; in other embodiments, polymeric amide or polyamide is substantially absent in a paving composition.
It is found that an amide compound, such as a diamide compound, can be used to enhance the adhesion between a bituminous material and mineral aggregate without using water. Thus, it functions as an anti-stripping agent. To make a paving composition, an amide compound is mixed with a bituminous material without adding water to the mixture. Mineral aggregates can be added to the mixture. After sufficient blending, the paving composition is ready for use. Preferably, the mineral aggregates are dried to remove moisture before being blended with the mixture. By substantially eliminating the presence of water in the paving composition, the adhesion between the mineral aggregate and the bituminous material is improved. Although it is preferred not to use water in formulating the paving composition, a small amount of water may be tolerated in the paving composition. In some instances, up to about 5 wt. % of water in a paving composition may be acceptable. Preferably, the water content is kept lower than about 4%, about 3%, about 2%, about 1% or about 0.5% by weight of the total composition.
Any bituminous material may be used in embodiments of the invention. Examples of bituminous materials include, but are not limited to, asphalt, tar, pitch, etc. A bituminous material includes, but is not limited to, any of various mixtures of hydrocarbons or other substances, occurring naturally or obtained by distillation from coal or petroleum, that are used for surfacing roads or for waterproofing. A preferred bituminous material is asphalt. Chemically, asphalts are complex aggregations of rather large aliphatic and cyclic hydrocarbon molecules. Besides the hydrocarbon content, additional constituents in asphalts may include oxygen, sulfur, and nitrogen (often in substantial quantities) and iron, nickel, and vanadium (present usually in trace quantities). Any amount of asphalt may be used. Preferably, asphalt is present in an amount of about 2% to about 10% or about 4% to about 8% by weight of mineral aggregate, and an anti-stripping agent is present in an amount of about 0.1% to about 5% or about 1% by weight of asphalt.
Any aggregate suitable for use in road construction or related applications may be used in embodiments of the invention. Although it is referred to as xe2x80x9cmineral aggregatexe2x80x9d herein, it need not be based on minerals. Suitable aggregate can be hydrophilic or hydrophobic, depending on the nature of the material. While the aggregate can include various mineral materials, such as cinders or stags, typically the aggregate is of natural origin, such as sand, rock, or the like, typically to the localities where the roads are being built, For example, limestone, dolomite, silica, sedimentary, metamorphic, or igneous rocks of various kinds are regularly used in road construction or related applications. Other types of aggregate, such as gravel, granite, trap rock, sandstone, etc., may also be used. Additional suitable aggregate is known in the art. Mineral aggregate may be present in any amount. Generally, mineral aggregate is about 80% to about 99% by weight of a paving composition, preferably from about 88 wt. % to about 95 wt. %, and more preferably from about 90 wt. % to 95 wt. %.
In formulating a paving composition, various additives may be used. For example, polymers, metal salts, polyamines, acids, petroleum hydrocarbon resins, etc., may be used in addition to a bituminous material, mineral aggregate, and an amide compound. These additives are, for example, disclosed in the following U.S. Pat. Nos. 3,868,263; 4,443,127; 4,447,269; 4,462,840; 4,721,529; 4,806,166; 5,109,610; 5,443,632; and 5,587,498. However, in some embodiments, the paving composition is substantially free of a polymer, such as an alkadiene-vinylarene copolymers and thermoplastic rubber polymers. In other embodiments, the paving composition is substantially free of metal salts, such as a divalent or trivalent metal salt of an inorganic acid. However, the substantial absence of these compounds do not necessarily mean they are absent in all embodiments of the invention.
Any amide compound which can promote the adhesion between a bituminous material and mineral aggregate may be used in embodiments of the invention. An amide compound refers to those co pounds which include at least one amide functional group. Preferably, an amide compound with two, three, four, five, six, seven, eight, nine, ten, or more amide functional groups is used in embodiments of the invention. A diamide compound can be present in a paving composition at various amounts such as about 0.1 wt. % to about 10 wt. %. about 0.5 wt. % to about 5 wt. %, 0.5 wt. % to about 2 wt. %, or about 0.8 wt. % to about 1 wt. %.
One class of suitable diamide compounds are represented by Formula 1 below. The diamide compounds can be made by reacting a dicarboxylic acid with a polyamine according to the following reaction scheme. 
In the above scheme, R1 can be any divalent hydrocarbyl group. The hydrocarbyl group may further include one or more functional substituents, such as a carboxylic group. Preferably, R1 is a branched or straight-chain alkyl group or aromatic or alkylaromatic group, preferably with from about 2 to about 54 carbon atoms per group. R2 and R3 in Formula 1 can be the same or different group, which is a branched chain alkyl group with from about 1 to about 6 carbon atoms or a straight-chain alkyl group with from about 1 to about 6 carbon atoms. Alternatively, each R2 and/or R3 can be xe2x80x94Rxe2x80x94NHxe2x80x94Rxe2x80x94 in which each R can be independently a branched or straight-chain alkyl group with from about 1 to about 6 carbon atoms. Additionally, R2 and/or R3 can be an aromatic or alkylaromatic group. In some embodiments, R2 and/or R3 can also be the same as R1. Moreover, R1 and R2 and/or R3 can be any organic functional group consistent with the stability of the resulting diamide molecule.
The resulting amide compound in Formula 1 may contain secondary or tertiary amide groups or both. The secondary amine is more reactive than the primary amine, but in the case of R2 and R3 being any hydrocarbon (not xe2x80x94Rxe2x80x94NHxe2x80x94R) there are twice as many primary amines present for the reaction. Depending on whether the primary amine or the secondary amine group reacts with the carboxylic acid, slightly different products will be obtained. If the primary amine reacts with the carboxylic acid either A or the B component will be a hydrogen atom (making the product a secondary amide) while the other component will be the rest of the polyamine. If the secondary amine reacts with the carboxylic acid either A or B will be xe2x80x94R2xe2x80x94NH2 while the other component will be xe2x80x94R3xe2x80x94NH2, making the resulting amide a tertiary amide. The thermodynamically preferred reaction is to form tertiary amides, however, depending on the reaction method and conditions, as well as what R2 and R3 are, the amount of secondary to tertiary amide can not be controlled. The products can be obtained pure, or as a mixture of products.
As described above, a diamide can be prepared by reacting a diacid with a polyamine. Any diacid that is capable of forming a diamide with an amine compound may be used. One class of suitable diacids is represented by Formula 2 below. 
Preferred diacids are represented by Formula 3 and Formula 4 below. 
Wherein x and y can be 0 or any positive integer. Preferably, x and y are integers from 3 to 9, x+y=12. Each Z in Formula 4 may be the same or different group, which is a carboxylic acid group or hydrogen, provided that both Zs are not hydrogen at the same time. In other words, at least one Z is a carboxylic acid group. In some embodiments, both Zs may be a carboxylic acid group (i.e., making the compound of Formula 4 a triacid.
In some embodiments, the diacid is a C21 carboxylic acid available as xe2x80x9cWESTVACO 1550xe2x80x9d from Westvaco of Charleston Heights, S.C. This C21 carboxylic acid is represented by Formula 5 and Formula 6 below. The molecule of Formula 6 is an isomer of the molecule of Formula 5. 
The polycarboxylic acids are obtained by reaction of carbon monoxide and water with an unsaturated acid, preferably oleic acid, as described by Reppe and Kroper, in Annalen der Chemie, 582: 63-65 (1953) in the case of Formula 3, and by Diels-Alder addition of acrylic, methacrylic, fumaric or maleic acid to polyunsaturated fatty acids with conjugated double bonds in the case of Formula 4, forming a cyclohexane structure. These acids are referred to as C19-dicarboxylic acid, C21-dicarboxylic acid and C22-tricarboxylic acid. Acids of this type are disclosed, for example, in U.S. Pat. Nos. 3,753,968 and 3,899,476 to Ward and U.S. Pat. No. 4,081,462 to Powers et al.
Other suitable polyacids and sources thereof include, but are not limited to, crude dimer-trimer acids such as xe2x80x9cDTC-195,xe2x80x9d xe2x80x9cDTC-298,xe2x80x9d xe2x80x9cDTC-409,xe2x80x9d xe2x80x9cDTC-295,xe2x80x9d xe2x80x9cDTC-275,xe2x80x9d xe2x80x9cDTC-155 dicarboxylic acids derived from fatty acids such as xe2x80x9cDIACID 1550xe2x80x9d (monocyclic C21 dicarboxylic acid); and xe2x80x9cTENAX 2010xe2x80x9d maleated tall oil fatty acid, all from Westvaco, P.O. Box 70848, Charleston Heights, S.C. 29415-0840. Other examples include, but are not limited to, xe2x80x9cSYLVADYM MX,xe2x80x9d xe2x80x9cSYLVADYM T-17,xe2x80x9d xe2x80x9cSYLVADYM T-18,xe2x80x9d xe2x80x9cSYLVADYM T-22,xe2x80x9d xe2x80x9cSYLVADYM T-35,xe2x80x9d xe2x80x9cARIZONA FA-7001xe2x80x9d and xe2x80x9cARIZONA FA-7002xe2x80x9d all available from Arizona Chemicals, 1001 East Business Highway 98, Panama City, Fla. 32401.
Suitable polycarboxylic acids are not limited to diacids. Carboxylic acids with three or more carboxylic acid groups may also be used. These acids can be produced from fatty acids, other carboxylic acids, carboxylic acid derivatives, alkylene or aryl diisocyanates, or mixtures thereof. These acids may include about 16 to about 36 carbon atoms per molecule, or from about 24 to about 54 carbon atoms per molecule. Polycarboxylic acids with about 4 to about 42 carbon atoms per molecule may also be used. In some embodiments, polycarboxylic acids may result from dimerization or trimerization of an acid, such as linoleic acid and oleic acid. These polycarboxylic acids may also be referred to as xe2x80x9cdimer acidsxe2x80x9d or xe2x80x9ctrimer acidsxe2x80x9d. For example, linoleic acid may dimerize via Diels Alder reaction, and oleic acid may dimerize over natural acid clay catalysts, such as montmorillonite. Therefore, in some embodiments, suitable polyacid materials may contain mixtures of dimer, trimer and tetramer groups. For example, dimer-trimer products (e.g., Westvaco xe2x80x9cDTCxe2x80x9d-series acids) may contain mixtures of dimer, trimer and tetramer groups.
Any amine compound or polyamine compound that can react with a polycarboxylic acid to produce an amide compound may be used in embodiments of the invention. One class of suitable polyamines is represented by Formula 7 below. 
As noted previously, R2 and R3 can be the same or different, and can be an alkyl group or a functional group containing an amine moiety, such as Rxe2x80x94NHxe2x80x94R in which each R is an alkyl group. Therefore, Formula 7 encompasses triamines, tetraamines, and any other higher amines, both straight-chained or branched. Suitable polyamines include, but are not limited to, alkylene polyamines, polyalkylene polyamines, aromatic polyamines, and mixtures thereof Examples of suitable polyalkylene polyamines include, but are not limited to, polyethylene and/or piperazine-based polyamines, such as diethylene triamine (xe2x80x9cDETAxe2x80x9d), triethylene tetraamine (xe2x80x9cTETAxe2x80x9d), tris-(2-aminoethyl) amine (xe2x80x9cbranched TETAxe2x80x9d), piperazinylethylethylenediamine (xe2x80x9cPEEDAxe2x80x9d), bis-(2-aminoethyl) piperazine (xe2x80x9cbis AEPxe2x80x9d), tetraethylenepentamine (xe2x80x9cTEPAxe2x80x9d), pentaethylene hexamine, aminoethyl-triethylenetetramine (xe2x80x9cAETETAxe2x80x9d), aminoethylpiperazinyltheyl-ethylenedianiine (xe2x80x9cAETETAxe2x80x9d), piperazinylethyl-diethylenetriamine (xe2x80x9cPEDETAxe2x80x9d), piperazinylethyl-hexyleneamine (xe2x80x9cPEHAxe2x80x9d), bis-hexamethylenetriamine (xe2x80x9cBHMTxe2x80x9d), and mixtures thereof Such compounds are available from suppliers such as Dow U.S.A. Chemical and Metals Department of Dow Chemical, Midland, Mich.; Bossco Industries, Inc., Houston, Tex. (e.g., TETA and higher ethyleneamine homologs available as xe2x80x9cB-AMINE 10-Axe2x80x9d from Bossco). Other examples of suitable types of polyamines include, but are not limited to, polyamines available from BASF Corporation, Air Products and Chemical, Inc. and Molex Company, Inc., Athens, Ala.
Triethylene tetraamine and diethylene triamine are preferred polyamines, which are represented by Formula 8 and Formula 9 below. 
Examples of suitable aromatic polyamines include, but are not limited to, the compounds represented by Formula 10-13 below. 
When a polycarboxylic acid is heated with a polyamine, a variety of reaction products may be obtained. For example, by blending two moles of diethylene triamine with one mole of C21 dicarboxylic acid, a bis-diethylene diamine salt is formed, which upon heating to about 200xc2x0 C. forms a diamidoamine of isomer Formulae 14A and 14B. 
In Formulae 14A and 14B, when A is H, B is (CH2)2NH(CH2)2NH2; and when A is (CH2)2NH2, B is (CH2)2NH2. Additionally, isomers of these side chains can be used or obtained.
Such a diamidoamine can be used as an anti-stripping agent to enhance the adhesion between asphalt and mineral aggregates. However, when the reaction mixture is heated, there are other competing reactions. For example, the diamidoamine of Formula 14 may undergo a ring closure to form an amidoimidazoline structure which is represented by Formulae 15A and 15B below. 
In Formulae 15A and 15B, when A is H, B is (CH2)2NH(CH2)2NH2; and when A is (CH2)2NH2, B is (CH2)2NH2. Additionally, isomers of these side chains can be used or obtained.
Prolonged heating of the compound of Formula 15A or 15B from about 230xc2x0 C. to about 280xc2x0 C. yields a diimidazoline of Formula 16A or 16B below. 
When a mixture of two moles of diethylene triamine and one mole of C21 dicarboxylic acid is heated slowly, the reaction product may be the diamidoamine of Formula 14A or 14B, the amidoimidazoline of Formula 15A or 15B, the diimidazoline of Formula 16A or 16B, or a mixture thereof. Such reaction products may be used as an anti-stripping agent in embodiments of the invention. Although the reaction products are exemplified by the reaction of a C21 dicarboxylic acid and a diethylene triamine, similar reaction products may be made with other types of polycarboxylic acids reacted with other types of polyamines. For example, C19 polycarboxylic acids and C22 polycarboxylic acids undergo similar chemical reactions as C21 polycarboxylic acids when reacted with a polyamine.
Other polyamines may or may not undergo ring closure reactions to form amidoimidazolines or diimidazolines. For example, the formation of amidoimidazolines is limited to polyethylene amines and polyamines characterized by at least one ethylene diamine functional group with at least three hydrogens attached to the two nitrogens. Compounds of this group which are able to give both amidoamines and amidoimidazolines are: ethylene diamine, diethylene triamine, triethylene tetraamine, tetraethylene pentamine, pentaethylene hexamine, and higher homologues-N-aminoethyl propane diamine, N,N-diaminoethyl propane diamine and the N-aminoethyl or N,N-diaminoethyl substituted butane diamines, pentane diamines and hexane diamines, and N-hydroxy ethyl ethylene diamine. These compounds have either the general formula:
xe2x80x83H2NCH2CH2NHR;
wherein
R=xe2x80x94H, xe2x80x94CH3, xe2x80x94C2H5, xe2x80x94C3H7, xe2x80x94CH2CH2OH, or xe2x80x94(CH2CH2NH)xH; and
x=1,2,3,4,5,6,7,8,9,or 10.
or
R1R2N(CH2)yNHR3;
wherein
R1=xe2x80x94H, xe2x80x94CH3, xe2x80x94C2H5, xe2x80x94C3H7, or xe2x80x94CH2CH2NH2;
R2=xe2x80x94H, xe2x80x94CH3, xe2x80x94C2H5;
R3 xe2x80x94H, xe2x80x94CH3, xe2x80x94C2H5, xe2x80x94C3H7, or xe2x80x94CH2CH2NH2; and
y=2,3,4,5,or 6.
Amines capable of forming amidoamines but not imidazolines are: 1,3-diaminopropane, 1,4-diaminobutane 1,5-diaminopentane, 1,6-diaminohexane, piperazine (1,4-diazacyclohexane), N-aminoethylpiperazine, N-hydroxyethyl piperazine, N-aminopropyl-propane diamine-1,3, N-methyl-N-aminopropylpropane diamine-1,3, N,N-dimethylpropane diamine-1,3, N,N-diethyl propane diamine-1,3, N,N-dimethyl-ethylene diamine, N,N-diethyl ethylenediamine; N-aminohexylhexane diamine-1,6.
The reaction products obtained from the reaction between a polycarboxylic acid and a polyamine may be modified by further reaction with reactive oxirane systems (such as ethylene oxide, propylene oxide or butylene oxide). Such reactions are disclosed in U.S. Pat. No. 4,447,269. The resulting modified reactions products may also be used in embodiments of the invention.
The paving composition in accordance with embodiments of the invention may be made by any method known or unknown in the art. For example, a bituminous material may be premixed with a suitable anti-stripping agent (e.g., a diamide compound) to obtain a bituminous mixture. Preferably, the mixing is conducted in the substantial absence of water. Consequently, the bituminous mixture is substantially free of water. Afterwards, mineral aggregates may be mixed with the bituminous mixture to form a paving composition. One or more suitable additives may be added at any stage of the process. Generally, the mixing is conducted at an elevated temperature, for example, from about 250xc2x0 F. to about 400xc2x0 F. (about 121xc2x0 C. to about 204xc2x0 C.).
The compositions can further comprise a fatty amine, a fatty propane diamine, a fatty amidoamine, a fatty imidazoline, a fatty monoquatenary ammonium salt, a fatty diquatenary diammonium salt, an ethylene glycol polyether of nonyl phenol, an ethylene glycol polyether of dodecyl phenol, or a mixture thereof. The compositions can also further comprise a nitrogen derivative of rosin acid, a nitrogen derivative of kraft lignin, or a mixture thereof.
A paving composition may also be made by mixing a bituminous material, an anti-stripping agent, and mineral aggregates simultaneously, preferably in the substantial absence of water. Such mixing is preferably conducted at an elevated temperature, for example, from about 150xc2x0 F. to about 400xc2x0 F. (about 66xc2x0 C. to about 204xc2x0 C.). Additional additives may also be added if desired. Still another method, for making a paving composition is to premix an anti-stripping agent with mineral aggregates and then subsequently add a bituminous material to the mixture at an elevated temperature. If desired, an anti-stripping agent may be diluted by a solvent before mixing.
An additional embodiment of the invention is directed towards methods of using the above-described compositions. The paving composition in accordance with embodiments of the invention may be used to construct or repair a road or used in other applications. One method of paving a road comprises obtaining a mixture of a bituminous material and a diamide compound, wherein the mixture substantially lacks water; adding a mineral aggregate to the mixture to prepare a paving composition; and applying the paving composition to a portion of a road. The obtaining step can comprise obtaining the mixture pre-made from a supplier, or mixing the components of the mixture. The applying step can be performed in the repair of an existing road surface, or in constructing a new road surface.
A method of paving a road in accordance with embodiments of the invention can comprise: (1) mixing a bituminous material with a reaction product of at least one, preferably two, polyamines reacted with at least one polycarboxylic acid, the mixing conducted in the substantial absence of water, thereby resulting in a bituminous mixture substantially free of water; (2) adding a mineral aggregate to the bituminous mixture to obtain a paving composition; and (3) applying the paving composition to a portion of a road. Preferably, the reaction product is an amide compound. The applying step can be performed in the repair of an existing road surface, or in constructing a new road surface. In some embodiments, the first and second steps may be completed in one step. In other embodiments, any one of the above steps may be practiced a number of sub-steps. In addition to the methods described herein for making and using a paving composition, other methods, such as those described in U.S. Pat. Nos. 4,447,269; 4,443,127; 4,721,529; and 5,019,610, may also be used in embodiments of the invention with or without modifications.
The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventors to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.